We propose to continue to follow the outcomes of 79 chronic offender juvenile delinquent males who were mandated to residential treatment by the local county juvenile court and who were randomized into an experimental treatment and a services-as- usual condition. The investigation has two primary goals: (1) to investigate whether treatment-initiated reductions in adolescent antisocial behavior result in changes in young adult adjustment, and (2) to examine the influence of social interactional, intra- individual, and contextual factors on young adult antisocial behavior to determine why treatment-initiated reductions are or are not maintained. The randomized trial contrasted the group home intervention currently used in the county with Multidimensional Treatment Foster Care (MTFC), a theory-based, multi-modal, individualized intervention. As predicted, initial results strongly favored the MTFC group in terms of reductions in subsequent criminal behavior, and the effect of treatment was mediated by the parenting practices active during the intervention. It is hypothesized that the initial positive impact of the MTFC treatment on delinquent youth and their families will lead to a cascade of positive impacts, including a reduced likelihood of antisocial behavior and related socially undesirable outcomes as well as an increased likelihood of prosocial adjustment during young adulthood. Processes and outcomes during each of the five years of the study will be assessed using a comprehensive strategy. Initiation, maintenance, and desistance of antisocial behavior will be examined as a joint function of past behavior and outcomes and current influences, most notably (1) social processes within peer, romantic, and family relationships, (2) contextual factors such as employment and neighborhood, and (3) intra-individual factors such as depression and substance use.